CRAMP Study Sites: Island of Ni‘ihau
Geographic Name: Ni‘ihau Island
CRAMP Site Code: Ni (5 Rapid assessment sites on the NE side of the island: Ki‘eki‘e, Kaununui, Keawanui, Pu‘ukole, and Lehua Island)
Geographic Location: 21° 55‘N; 160° 10‘ W
Map of Ni‘ihau . (Click for larger view)
NOAA Chart of Ni‘ihau and Kaua‘i. (Click for larger view)
NOAA Chart of Ni‘ihau. (Click for larger view)
Physical Features (Physiography) - General Bathymetry, Topography:
Kaua‘i, Ni‘ihau and Kaula are the eroded emergent portions of three shield volcanoes that stand in 2000 fathoms (12000 feet) of water. The Kaulakahi channel separating Kaua‘i from Ni‘ihau is 600 fathoms (3600 ft) in depth. To the southwest, Ni‘ihau is separated from Kaula by water depths of 600 fathoms (3600 ft). Ni‘ihau is the seventh largest of the eight main Hawaiian Islands with an area of 70 square miles (18,650 ha.). The center of the island is a high plateau with a maximum elevation of 390 m (1281 ft) at Pānī‘au. The north and east sides of the plateau are steep cliffs, varying between 180 and 300 m in height. The south and western slopes are gradual. Twelve "lakes" exist on the coastal plain, the largest being Halāli‘i Lake and Halulu Lake. The lakes normally are dry, but fill during periods of heavy rainfall. Some of the small lakes form behind the coastal sand dunes. Rainfall is low (<25 inches annually) on the western coastal plain, but increases with elevation to 30-35 inches annually on the elevated plateau and over 40 inches annually on the upper windward (NE) slopes. There are no perennial streams. Vegetation over most of the island consists of Kiawe and lowland shrubs. The steep slopes along the windward (NE) portion of the island reportedly support lush vegetation that is typical of areas experiencing higher rainfall. A small estuary exists at the mouth of the intermittent Keanauhi Stream on the west shoreline of the island. Geology and groundwater resources are described by Stearns (1967). Sandy beaches are present along much of the northwest coast. Reefs are found mainly along the western coastline. Two small uninhabited islands lie off Ni‘ihau. Lehua is located 1 km north of Ni‘ihau. Kaula is located 34 km to the south-west. There is a pinnacle called "5 fathom pinnacle" approximately 3 miles WNW of Kaula Rock on the Kaula bank.
This island is not in the wave shadow of any other large island and thus is exposed to full impact of large ocean swell from all directions.
Reef Structure, Habitat Classification:
The coastline of Ni‘ihau is approximately 45 miles in length. Reefs of Ni‘ihau are poorly developed due to extreme wave energy from all directions. Reefs of Ni‘ihau probably are damaged occasionally by hurricane waves. Hurricane Nina (November 1957) brought surf of 35 feet to Kaua‘i's southern coast. Hurricane Iwa struck Kaua‘i in November 1982 with extensive damage to the reefs. Hurricane ‘Iniki struck Kaua‘i in September 1992 and again caused extensive reef damage along the south and west shores. Presumably the reefs of neighboring Ni‘ihau experienced similar destruction. Ni‘ihau does not have any substantial bays that could shelter coral development. The island is of insufficient size to protect portions of its coastline from wave refraction effects.
Extreme northwest swell frequently impacts the north and western shores of Ni‘ihau during the northern hemisphere winter. The WAM Wave Model data (Courtesy of the US Naval Oceanographic Office) as shown above for January 13, 2001 demonstrates the severity of impact. South swell impacts the southern coast during the northern hemisphere summer. (Click for larger view)
Pinnacles, overhangs, underwater caves and vertical walls exist along the northwest shoreline and biologically rich reef communities are said to occur off the south end of the island. However, little scientific information is available. Where corals are found, they reportedly exist as thin veneers on limestone and basalt outcrops. High-wave energy coral communities dominated by Pocillopora meandrina and Porites lobata appear to be most common (Naughton, J. Personal communication 2000).
Adjacent Land Tenure, Land Use:
The Robinson family has privately owned the island since 1864. The island is operated as a cattle ranch.
Human Use Patterns:
Chart of Lehua Island and the NW portion of Ni‘ihau. (Click for larger view)
The island is closed to the public, so there is no recreational visitor industry. Private boats, commercial fishermen and dive charters occasionally visit the reefs, but visitors are not allowed to come ashore. Most of the commercial operators confine diving and snorkeling trips to the northern tip of the island. Spectacular dive spots exist in the area around the NW portion of Ni‘ihau and Lehua Island (Andrew Ellis, personal communication 2000; John Naughton, personal communication 2000). Vertical walls plunge to great depths, with clear water and abundant fish life. Pelagic fish such as tuna can be observed swimming close to the vertical walls. Pinnacles, caves and other features provide interesting places to explore. Black coral is abundant and occurs as shallow as 90-feet off the north end of Ni‘ihau. Some excellent diving locations exist at the SE tip of the island, but strong currents can occur in this area. Few commercial dive boats are of sufficient size to cross the Kaulakahi channel and take dive tours to Ni‘ihau, but only during ideal weather and wave conditions. During 25 knot Trade Wind conditions, the NE swell can exceed 15-25 feet and conditions in the smaller dive charter and fishing charters are very uncomfortable for tourists. Commercial fishing boat crews are more capable of handling rough seas, but generally avoid crossing the Kaulakahi channel during high trade wind or north swell conditions. Consequently, fishing pressure along much of the Ni‘ihau coastline is light compared to most of the main Hawaiian Islands. The inhabitants of Ni‘ihau depend on these reefs for a large part of their subsistence. Kaula island is in use as a military target range, but only inert warheads have been employed in recent years.
Fishing pressure on the reefs is still very low in comparison to other islands. Favored target species such as kūmū, u‘u, and uhu are of large size and high abundance (Naughton, personal communication 2000). However, fishing activity on the reefs has been increasing steadily over the past 25 years. The NE shoreline is a popular fishing area when weather and surf permit due to the presence of complex bathymetry and an abundance of the high-value "redfish" that inhabit holes in the reefs.
Status (Degree of Legal Protection):
There is open access to the reefs, but shoreline above high tide mark is under private ownership and trespassing in forbidden. Kaula is occasionally closed to boating during military exercises. The remoteness of this islet combined with rough sea conditions have served to protect the reefs from extensive human use. Authority for managing the marine resources within three miles (4.8 km) of the high tide mark lies with the Division of Aquatic Resources, Department of Land and Natural Resources. All laws pertaining to the management of state marine resources apply (see pamphlet "Hawai‘i Fishing regulations, September 1999", 51 pp. available from Division of Aquatic Resources, Department of Land and Natural Resources, Kalanimoku Building, 1151 Punchbowl St., Rm. 330, Honolulu, Hawai‘i).
Management Concerns (past, present and future):
Proposals for any changes in use of the island have been rejected. Human impact on the reefs at present is probably minimal. The impact of fishing by recreational and commercial fishing/dive boats coming from Kaua‘i has not been determined, but is believed to be low. However, the number of boats visiting Ni‘ihau has increased noticeably over the past 25 years (Naughton, personal communication 2000). There are undocumented rumors that destructive fishing practices (i.e. bleach fishing) might be employed by unscrupulous fishermen who visit Ni‘ihau. The remoteness of the island and so few observers would provide some protection to such lawbreakers.
Noteworthy Flora and Fauna:
Unique marine life includes a growing population of the endangered Hawaiian Monk Seal, Monachus schauislandii. This population has grown in number to about 35 animals over the past 8-10 years. From 10 to 12 pups are born on Ni‘ihau annually. Kaua‘i, in contrast, has a resident population of only about 10 Monk Seals. Monk Seals are curious, and will investigate SCUBA divers. Seals will visit divers, especially along the NW coast and at Lehua Island. The Knifejaw (Oplegnathus spp.) is a fish found in Japan and the western Pacific. Two species of this genus are occasionally seen in the Northwestern Hawaiian Islands but rarely seen in the main Hawaiian Islands. Knifejaws have been observed at Ni‘ihau (Naughton, personal communication 2000), although they are quite rare. Sharks are still numerous off Ni‘ihau, and especially at Kaula. A large aggregation of grey reef sharks forms off of Ki‘i on the NE side of Ni‘ihau every May. Such aggregations probably involve breeding activity (Naughton, J. personal communication 2000). These aggregations are common in the Northwestern Hawaiian Islands (Laysan, Necker, Nihoa), but are not known in the other main Hawaiian Islands. Divers report the presence of a large shark that is either a white shark or a large tiger shark off Lehua. Abundant and diverse populations of reef fish, sharks, etc. are associated with the "5 fathom pinnacle" located 3 miles WNW of Kaula Rock (Naughton, personal communication, 2000).
Sightings of an endangered loggerhead turtle have been made in Lehua Channel (Andrew Ellis, personal communication, 2000). Manta rays, and other large fish are still abundant because this area is still only lightly fished. A reef coral that is rare in Hawai‘i (Cosinaraea wellsi), has been reported at a depth of 120 ft. (37 m) (Maragos 1977).
The population of approximately 230 residents is largely of Hawaiian ancestry. The primary language of the island is Hawaiian. Ni‘ihau is the only community that uses the Hawaiian language with an unbroken tradition since before western contact. This core of mānaleo (native first language speakers) is a valuable cultural resource, especially since there is renewed interest in reviving the Hawaiian language in communities throughout the state. Lei made locally from "Ni‘ihau Shells" are treasured cultural items.
Scientific Importance and Research Potential:
The reefs of Ni‘ihau are unknown to science due to lack of adequate surveys. Quantification of the reef fish stocks in lightly fished areas are needed to establish a baseline comparison to more heavily fished areas in the Main Hawaiian Islands.
A general survey of the reefs of Ni‘ihau is needed, as virtually no information exists at present. One focus of the survey should be the identification of possible marine protected areas.
Last Update: 04/21/2008
By: Lea Hollingsworth
Hawai‘i Coral Reef Assessment & Monitoring Program
Hawai‘i Institute of Marine Biology
P.O. Box 1346
Kāne‘ohe, HI 96744